396 PROCESSES INFERRED FROM DIRECT OBSERVATION 



to turn in again to kill time and also to keep warm for I feel the cold 

 very much now." 



"At 10 A.M. I get up to dress Xavier and prepare food, but find 

 him in a kind of fit. Coming round a few minutes later, he ex- 

 changed a few words and did not seem to realize that anything had 

 happened . . ." 



"During the afternoon he had several more fits, then became delirious 

 and talked incoherently until midnight, when he appeared to fall off 

 into a peaceful slumber. . . After a couple of hours, having felt 

 no movement from my companion, I stretched out an arm and found 

 that he was stiff." 1 



These are not symptoms of mere inanition. Definite intoxication 

 was also present, and it appears not improbable that the extraordinary 

 exertions necessitated by their situation, carried out as they were upon 

 an almost exclusively protein diet, may have led to the abnormal 

 disintegration of food- and tissue-proteins by the muscular tissues, with 

 the production of poisonous nitrogenous, fragments. 



The employment of a high protein diet as a preparation for muscular 

 exertion and endurance is therefore in the highest degree irrational, 

 more especially since the rate of loss of heat from the body on a protein 

 diet is diminished, so that the cooling necessary for the maintenance of 

 prolonged bodily effort is rendered more difficult than usual. The 

 only possible ground for the formerly popular dietary of beefsteak for 

 athletes is the fact that on a diet purely of flesh the muscular machine is 

 more efficient, i. e., produces less heat per unit of external work per- 

 formed. In fact in a dog fed upon pure flesh Pflueger obtained the 

 highest work-yield that has ever been observed, nearly fifty per cent, 

 of the heat-value of the food appearing as mechanical work. For a 

 short, sharp "dash" or brief effort, therefore, a high protein diet may 

 possess advantages, but for prolonged extreme exertion a mixed diet 

 containing an exceptionally abundant allowance of carbohydrates is 

 the only rational prescription. This is, in fact, the actual dietary 

 which, in the absence of suggestion or direction, is voluntarily chosen 

 by those classes and groups of individuals whose mode of earning a 

 living compels great and sustained muscular effort. 



The normal source of muscular energy is therefore the carbohydrates 

 of the dietary. That the Fats may also be utilized for this purpose is 

 evidenced by the fact, first established by Rubner, that fat and carbo- 

 hydrate are Isodynamic Foodstuffs, i. e., that equicalorific amounts of 

 these substances can replace one another in the diet. There has been 

 some discussion of the question whether or not the fats are directly 

 utilized for the performance of work, or whether they may not have 

 to undergo a preliminary transformation into carbohydrates. This 

 question has been experimentally investigated by Zuntz, who found 

 that when carbohydrates predominate in the diet the total amount of 



1 The Home of the Blizzard, Sir Douglas Mawson, London, 1915, vol. i, pp. 258-259. 



